Wurtz reaction
Two molecules of an alkyl halide react with sodium in dry ether to give a higher alkane with double the carbon atoms of the alkyl group.
BromoethaneCH₃CH₂BrHaloalkane - Step 1
Na, dry ether
ButaneCH₃CH₂CH₂CH₃Alkane
How it works
- Sodium reacts with the alkyl halide to form an alkyl sodium (or radicals).
- The alkyl group attacks a second molecule of halide.
- The new C-C bond forms and NaX is lost.
What it makes
Symmetrical alkanes with an even number of carbons.
Where it fails
A mixture of two different halides gives three alkanes, so it is used for symmetrical alkanes only. Methane cannot be made.
Class 11, Chapter 9 Hydrocarbons
Wurtz reaction: quick answers
Why must dry ether be used?
Sodium reacts with water, and moisture would destroy the alkyl sodium.
Can the Wurtz reaction make methane?
No, it joins two alkyl groups, so the smallest product is ethane.
What does a mixture of CH3Cl and C2H5Cl give?
A mixture of ethane, propane and butane.